TRS-80 Computers: TRS-80 Model I

Remember the CB craze? From nothing in 1970 to over 20% of the corporate business in the early 70’s, CB radios not only contributed to Tandy’s profits, but brought an entire new group of customers into Radio Shack stores. Indeed, things were so good in electronics that Tandy Corp. sold off all its other subsidiaries including the original, Tandy Leather, in 1975. But the abrupt collapse of the CB craze in 1977 left the company in disarray.

Enter Don French and John Roach. Roach had joined Tandy in 1967 as a data processing manager and, by 1976 had been promoted to vice president of manufacturing. Don French was on the West Coast in the heart of Silicon Valley and had been trying to get Radio Shack involved in computers, even though his boss, Bernie Appel (recently promoted to president) was opposed. In mid-76, Roach and French were traveling together on the West Coast and stopped in to see National Semiconductor’s new SC/MP microprocessor. While there, they met Steve Leininger who briefed them on the hardware and software. Roach and French were impressed with Leininger and wanted to hire him to do some consulting. However, the National Semi marketing people refused to part with Leininger’s address or phone. Next stop on the itinerary of Roach and French was Paul Terrell’s Byte Shop on El Camino Real. What a surprise when they found Leininger moonlighting there as the night sales clerk. They asked him about consulting, but four weeks later asked him to come down to Ft. Worth to see the facilities.

At the end of the day, Roach offered him a job on the spot. Leininger accepted but found that Tandy wasn’t really committed to a computer just yet. For six months he, in his words, “played around with a couple of things–an audio pre-amp, a computer kit, and some other minor projects.” But as CB turned more and more sour, there was a growing cry at Tandy for something new. They finally moved Leininger off into a room of his own with instructions to build a computer. Leininger remembers it well, “It was there that I wire-wrapped the predecessor of the Model 1. I even put Tiny Basic with the graphics extensions in a 2K ROM.” (Tiny Basic was written by Dr. Wang at Stanford and placed in the public domain. Leininger had helped implement it for People’s Computer Company.

The Birth

The first ‘Tandy’ computer was the Radio Shack (TRS – Tandy Radio Shack) TRS-80. Called just the TRS-80, it later became known as the “Model I” when the TRS-80 Model II was announced in the summer of 1979.

The Model I was invented by Don French (A buyer for Tandy) & Steve Leininger (The head of the Homebrew Computer Association) and first announced on Wednesday, August 3, 1977, in Radio Shack Press Release 7741-A, at a press conference at the Warwick Hotel in New York City.

Radio Shack said they anticipated deliveries to start in two weeks, but was quite unsure of the product, thinking that they might sell 600 to 1000 the first year. It was also the most expensive single item Radio Shack had ever carried to that date. They required a $100 deposit to place the computer on order. In actuality 10,000 units were sold in the first month! Radio Shack was swamped with orders, and delivery times quickly fell to months after order. By early November of 1977, Radio Shack was delivering 16K RAM units with 5 digit serial numbers that had been ordered in early September. At that time, there were separate serial number sequences for 4K and 16K machines.

The Model I began with a $599 Level I System with 4K RAM, monitor, and cassette, with all cables and adapters ready to go (except that it took 3 plugs, so you probably needed to purchase a power strip). The Level 1 was soon replaced by a 16K Level II System. The Level II (first model) was updated to include a numeric keypad.

The Evolution

Soon after Level II showed up the Expansion Interface was made available for $299. The Expansion Interface had room for an additional 2 banks of 16K RAM and an RS-232 card. In addition the Expansion Interface already contained a floppy disk controller and a control circuit to allow two cassettes to be hooked up at one time and controlled by the computer. The Expansion Interfeace was a change from the original announcement, which declared that there would be an expansion box with a 5 slot S-100 chassis for the unit. (No price was ever given for the S-100 box that I recall.) Mike Yetso has advised that there was also an 8K RAM for an additional $99, but only a few of those were ever made, and Mike does t believe ANY customers EVER got an 8K upgrade kit — with all 8K computers being upgraded to 16K.

Disk drives showed up the following year for $500. These were Shugart SA400 drives with about 80K of storage. The Centronics Line printer showed up as well.

The Death

The Model I was discontinued in January of 1981 due to its failure to meet the FCC’s Radio Frequency Interference rules. By the time it was discontinued, the Model I had sold over 250,000 units (which was 197,000 more units than Tandy’s CEO had intended to manufacture). A Model I (with Expansion Interface and Floppy Drives) is currently housed in the American History Museum at the Smithsonian Institute.

What is a Computer

Not too many years ago. the pocket calculator we take for granted today could have passed for a powerful computer, and one worth a great deal of money Today, however, there is much more to the definition of a computer.

The computer is in some respects like a super-power calculator, yet it is very different. Calculators work with numbers. They add. subtract, multiply and divide. Computers work not only with numbers, but with alphanumeric data -names, words, stock numbers. A computer can be programmed to repeat the same function over and over. It can compare a list of stock numbers with one you have asked it to find or alphabetize a list of names. It can logically evaluate information given to it, and act on its findings. It can store large volumes of data for future use or reference. It can converse with its operator, asking questions like “Your totals don’t balance. would you like to put the data in again?” or “Would you like the results printed out, or displayed on the video screen?’.

Obviously, a computer is much more than just a “number-cruncher.” It is literally an extension of the mind. It is to man’s mind what the lever is to his arm – a machine capable of increasing his effectiveness. It can free you from repetitive exercises which do not require human judgement. It can provide facts and figures with extreme speed, giving you the time to exercise your judgement thoughtfully.

Not many years ago, a computer with the power of the TRS-80 would have cost over a million dollars. The equipment would have filled large rooms. The advancing technology of integrated circuits led to the microprocessor – literally a “computer on a chip.” This, in turn, drastically reduced the size and cost. The TRS-80, a product of these advances. is manufactured and sold only by Radio Shack.

Perhaps the best way to really explain the computer is to ask the question …

What does a computer do?

What does a computer do? Not too many years ago. the pocket calculator we take for granted today could have passed for a powerful computer, and one worth a great deal of money Today, however, there is much more to the definition of a computer. The computer is in some respects like a super-power calculator, yet it is very different. Calculators work with numbers. They add. subtract, multiply and divide. Computers work not only with numbers, but with alphanumeric data -names, words, stock numbers. A computer can be programmed to repeat the same function over and over. It can compare a list of stock numbers with one you have asked it to find or alphabetize a list of names. It can logically evaluate information given to it, and act on its findings. It can store large volumes of data for future use or reference. It can converse with its operator, asking questions like “Your totals don’t balance. would you like to put the data in again?” or “Would you like the results printed out, or displayed on the video screen?': Obviously, a computer is much more than just a “number-cruncher.” It is literally an extension of the mind. It is to man’s mind what the lever is to his arm – a machine capable of increasing his effectiveness. It can free you from repetitive exercises which do not require human judgement. It can provide facts and figures with extreme speed, giving you the time to exercise your judgement thoughtfully Not many years ago, a computer with the power of the TRS-80 would have cost over a million dollars. The equipment would have filled large rooms. The advancing technology of integrated circuits led to the microprocessor – literally a “computer on a chip.” This, in turn, drastically reduced the size and cost.

The TRS-80, a product of these advances, is manufactured and sold only by Radio Shack. Perhaps the best way to really explain the computer is to ask the question. . . Large computers are well known in the business world for their ability to do bookkeeping, billing, payroll, inventory control. and analysis and forecasting of business data. Laboratories, engineering firms and universities have used computers to analyze volumes of data and numbers in a wide variety of applications.

As we said, a computer works with alphanumeric information, not just numbers. It can alphabetically sort a mailing list, find subscribers who have not renewed, locate slow-moving inventory items, write purchase orders based on sales trends and current inventory levels, or simply catalog your butterfly collection. And it can become an automated teacher of math, spelling. American history or what have you. For entertainment you can spend hours playing really challenging computer games, from chess to space war. The TRS-80 Microcomputer System is capable of performing all of these activities. In general. it differs from its larger cousins in speed and the amount of information which can be kept on line at any one time. Keep in mind the TRS-80 isn’t a panacea -it’s a computer. Study your needs carefully and buy the TRS-80 system that’s right for you – expansion could be the answer. For example, a simple Level-! 4K inventory system could handle 22 items (64 characters per item), while a disk system TRS-80 could store about 1300 items per data diskette. Remember, too, that you’ll need to write programs (our manual tells you how) or have them prepared to suit your specific needs. Visit a nearby Radio Shack for help in choosing your system.

Why a personal microcomputer? Because today’s complex lifestyles require a method of getting more things done in less time. The TRS-80 has made true computing a reality for the small business, laboratory, classroom and the home. Radio Shack’s TRS-80 is the personal computer for anyone and everyone!

The TRS-80 System

Radio Shack’s TRS-80 Microcomputer System is fully wired, tested and U.L. listed for electrical safety – you can put it to work immediately! It’s ideal for finances, education, accounting, lab use – even for home entertainment. And it’s the computer with a full line of accessories being delivered now with more to come in the future.

The TRS-80 comes to you ready to be programmed, either from pre-recorded cassette tape or from the keyboard. A “program” is simply a set of step-by-step instructions telling your TRS-80 what you want it to do. The TRS-80’s programs are written in easy-to-learn, plain-English BASIC programming language (BASIC stands for “Beginner’s All-Purpose Symbolic Instruction Code”). The user’s manual includes a beginner’s course in BASIC that’ll have you “talking” to your computer in no time. The TRS-80 talks back to you via its 12-inch video screen.

Inside the 53-key professional keyboard housing is the actual “brain” of the computer – a powerful Z-80 microprocessor that serves as the central processing unit (CPU). Programs and data are stored in internal “memory chips.” Our lowest-priced TRS-80 computer contains 4096 bytes (4K) of user memory, or RAM (a byte being roughly equivalent tp one typewritten character and made up of eight electrical signals called “bits”). It can be expanded to 16K within the keyboard unit and to 48K by using the Expansion Interface with additional memory options.

Note – the Z-80 is an 8-bit microprocessor and can address a total of 64K of memory. Both ROM and RAM are addressed in the TRS-80, along with some internal “overhead.” In a 48K RAM configuration, the last memory address is 65,535 -the usual ending address for a 64K computer.

The “Read-Only Memory” chips contain the “BASIC interpreter” software. The interpreter accepts plain-English commands and statements from the programmer and translates them into the numeric language ofthe Z-80. You can access the 2-80’s numeric “machine language” directly by using our “T-Bug” monitor program, available on cassette tape, or in “assembly language” by using our “EditorLAssembler” tape. (Both of these tapes are suggested only for advanced programmers with a knowledge of machine and assembly language.)

The Realistic cassette recorder lets you record and play your own programs or use one of Radio Shack’s prepared programs – simply run the cassette and begin computing. The recorder is included free of extra charge with each basic TRS-80 system. Other recorders may be used – with varying degrees of success – but only if they have automatic recording level capability

The video monitor looks like a standard television set without the channel selector. It features a wider bandwidth than most TV sets for a shatper display of printing and graphics. The monitor operates on ordinary 120-volt AC. 60 Hz house current. Foreign versions are available in other countries and are sold only overseas by Tandy Electronics outlets. The computer cannot be connected directly to a standard TV set.

For access to other hardware, the TRS-80 utilizes a unique 40-pin bus (connector system) that can attach the TRS-80 to our Expansion Interface, or other external devices. Housed in the finest ABS material, the TRS-80 is virtually unbreakable. It may be left “on” for extended periods of time with no adverse effects, as long as the cooling vents are not obstructed.

Why the TRS-80

Low Cost. Seldom has such a technologically advanced piece of electronic equipment been made affordable to the general public. But Radio Shack broke the price barrier, and made the personal computer a reality.

Value. Most people regard their TRS-80 as an investment, and often it yields a return that exceeds their fondest dreams. That’s because TRS-80 is what a personal computer should bea powerful system that’s easily expandable.

Availability. The TRS-80 and its accessories are supplied through Radio Shack outlets nationwide and we have over 5800 locations. You can stop in at one near you and actually see and try the TRS-80 before deciding on your purchase.

It’s easy to Use. Our Level-I TRS-80 system allows the user to learn programming with absolutely no previous knowledge of computers or programming. Our superb user’s manual is written in a light and humorous style that makes learning fun. And the TRS-80’s BASIC language is stored in permanent Read-Only-Memory (ROM), so it’s ready to use the second you turn on the power.

It’s expandable. Even the smallest TRS-80 system can be expanded into our largest business system – and you pay no “premium” for not having purchased the biggest system in the beginning. With the Expansion Interface you can add more memory for a system with up to 48K RAM, plus printers, disk drives and much more. And you can convert to one of the most powerful microcomputer languages available. our Level-II BASIC.

We build it ourselves. To insure highest quality at an afiordable price, Radio Shack designed the TRS-80, and we build it in our own factories. We have taken maximum advantage of state-ofthe- art engineering and our manufacturing expertise to produce the best value-to-cost ratio on the market.

Service. If repairs are ever needed, Radio Shack has a nationwide network of over 50 service centers to minimize “down time.” You simply return the component in need of service to your nearest Radio Shack store – we do the rest.

Reputation. Radio Shack, with 58 years’ experience to our name, is the nation’s leading electronics retailer. We’re backed by our NYSE-Listed parent, Tandy Corporation. You can depend on us in the years to come to stand behind our product and to offer an ever-growing line of both accessories and programs.

Who can use the TRS-80?

Thousands of people from all walks of life already own the TRS-80 Microcomputer. Why? Because they saw that it could serve to enrich their lives. At work and at home. the TRS-80 is exceptionally versatile. And that’s why so many people are using it.

Businessmen find the TRS-80 gives them the edge on the competition. So much of their time is spent on tedious, repetitious paperwork that they often find little time to devote to the more productive areas of their job. But with a TRS-80, tasks like inventory, general ledger posting, payroll and accounts receivable can be processed quickly and effectively. Accountants find it invaluable in tax preparation, cost accounting and in keeping clients’ records.

Engineering firms, manufacturers and large businesses use the TRS-80 for specific jobs too small or too costly to run on a large computer.

The TRS-80 is an invaluable – yet affordable – educational tool. Computer-assisted instruction is ideal for students who require repetitive instruction and immediate evaluation of their progress.

And homeowners find more uses for the TRS-80 every day. Already they use it to manage the household budget and to keep purchase dates, serial numbers and repair history of home appliances and valuables.

How do owners like our TRS-80? A school system tells us that the TRS-80 has made computer-assisted instruction available to them for a fraction of their previous cost per student-hour. A Civil Engineer reports laborious structual concrete beam calculations requiring hours are now completed in less than ten minutes. A father writes to tell us “this investment is one of the most significant in value to our family and to the future education of our child that we have ever seen.”

The limits of what the TRS-80 can do depend upon the creativity of the user, and his or her needs and imagination. As an educator put it, the TRS-80 “makes possible the tapping of human innovation and creativity on an unprecedented scale.”

The Offerings

On display at over 7000 Radio Shack Locations, TRS-80 Model I is a microcomputer you can see and try before you buy. It’s a proven system, used by business people, professionals, and “just plain folks” everywhere for accounting, education, lab work, budget management, word processing – even games at home. Model I comes wired, tested, and ready to operate. It is supported by our growing line of software (programs for specific jobs) and accessories which are available either “off-the-shelf” or on a quick-delivery basis wherever you see the Radio Shack sign.

4K, Level I “Starter” System (26-1051): Our lowest-priced Model I TRS-80 computer contains 4K bytes (4096 characters) of RAM (Random Access Memory). RAM is internal memory space accessible to the user for program and data storage. This system is programmed in “Level I BASIC”, an easy-to-learn computer language that’s ideal for beginners. To get an idea of the system’s capabilities “right out of the box,” see the Level I software listed on page 9. The 4K, Level I system is modular and can be upgraded at any time to meet future requirements. Includes computer/keyboard unit, 12″ video monitor, cassette recorder, game cassette, and a superbly written user’s manual that teaches you to write your own programs. U.L. Listed.

16K, Level II System (26-1056): Level II is an advanced version of BASIC that offers vastly increased computing power and advanced programming features for greater versatility. The 16K, Level II system is the “standard” Model I ooniguration and ideally suited to many small business and professional jobs. It can be equipped with a printer and other accessories shown on the facing page. Includes all Level I hardware and Level II Reference Manual. Computer/Keyboard unit includes built-in 12-key numeric datapad. U.L. Listed.

BASIC

Level I

Radio Shack’s Level-I BASIC really packs a lot into 4K of ROM to produce a thorough but easy to understand computer language. It’s the ideal entry level programming language for the computer novice. In fact, BASIC is an acronym for “Beginner’s All-purpose Symbolic Instruction Code.” Level-I includes most standard BASIC commands, video graphics, cassette input/output, floating point arithmetic, numeric array, and limited string variables. If .you can read and write English, you can probably learn to program with Level-I BASIC!

The Radio Shack TRS-80 Level I language is the way to learn computer programming. It’s a simplied version of the BASIC (Beginner’s All-Purpose Symbolic Instruction Code) programming language, and allows you to “talk” to the computer using simple English commands and statements. Even if you have no prior knowledge of computer operation or the writing of programs, our easy-to-understand teaching manual lets you quickly learn how to program the TRS-80. Level I includes most standard BASIC commands and also several outstanding features, such as a screen display of 16 lines of 64 characters. 48×128 video graphics, 250-baud cassette input/output rate, floating point arithmetic, 6-digit numeric accuracy, single dimension array, limited string variables, command abbreviations, and error codes. Level I is stored in 4K of Read-Only Memory so it’s ready to use the instant you turn on your TRS-80 Computer.

Level II

If you’re experienced with Level I, be prepared for some pleasnat surpises with Level II. Level II is a far more advanced or “extended” version of of BASIC, and offers vastly increased computing power (its execution time is 30% faster than Level I’s) and additional features. You can choose a screen format of 16 lines of either 32 or 64 characters – both with automatic scrolling, and the 500-baud cassette input/output rate is twice as fast as Level I. In addition, Level II offers multi-dimension arrays, comprehensive string variable handling, automatic line numbering, tracing, PEEK and POKE, call-up of machine language routines, printer commands, and 23 specific error messages.

Versatile program editing with extensive editing commands allows easy modification of your programs. Level II offers increased numeric accuracy of up to 16 significant digits; intrinsic functions remain at 6-digit accuracy. Program lines, logical lines, and string variables may be up to 255 characters long (overflow moves to the next screenline). A compressed storage format allows some programs to be stored in fewer bytes of memory than in Level I. Level II is stored in 12K of Read-Only Memory, and comes with a comprehensive reference manual.

Disk Basic

The TRSDOS operating system includes the software and input/output functions needed to operate the TRS-80 Disk System. TRSDOS allows vast file storage space, expanded file manipulations, and much quicker access time than you get with tape storage. Disk BASIC allows you to access files either randomly or sequentially, and programs may be stored in BASIC as ASCII or in compressed format files to save storage space.

Radio Shack’s Disk BASIC is a further extension of the Level II language. A few of Disk BASIC’s extension commands are DEF FN – allows userdefined functions. HEX CONSTANTS – allows you to enter hexadecimal and octal constants by preceding them with “&H” or “&”, and TIME$ – returns date and time as a text string.

File commands include CLOSE – closes a file which is currently open, LOAD-loads a BASIC program from disk into memory. MERGE – combines a BASIC program with another program currently in memory. OPEN – opens a file for use. This command specifies sequential/random input or output, the file number, and file name. SAVE-saves a BASIC program onto disk. (You can CLOAD a tape program, then easily put it on disk.)

For more technical applications, the “Engineer” system combines powerful level II with 16K of RAM. The new Printer Interface cable allows direct connection of the Quick Printer to TRS-80’s bus connection, without using the Expansion Interface. Quick Printer provides 80-column hard copy and program listings. The Space-Save holds the entire system and provides the user with ample work space.

“Professional” 16K System

N/A

$2,384.00

Consists of:

•

16K Level II Complete System

•

Expansion Interface

•

Mini-Disk System

•

Quick Printer Cable

•

System Desk

Mini-disk for expanded language, fast data handling, and approximately 49,900 bytes of user disk storage space. Quick Printer provides 80-column hard copy and prorgam listings. System Desk holds the entire system with plenty of work space left over.

“Business” 32K System

N/A

$3,294.00

Consists of:

•

16K Level II Complete System

•

Expansion Interface 16K RAM

•

2 Mini-Disk Systems

•

Line Printer II and Cable

Two mini-disk units give user approximately 135,600 bytes of disk storage. Virtually all TRS-80 disk-based business software requires this as a minimum system. Applications include general ledger, payroll, disk mail list, and more. Line Printer II adds real versatility and convenience to this system, without taking up a lot of work space.

“Deluxe Business” 32K System

N/A

$4,191.00

Consists of:

•

16K Level II Complete System

•

Expansion Interface 16K RAM

•

2 Mini-Disk Systems

•

Tractor Feed Line Printer and Cable

•

System Desk

•

Line Printer Stand

Approximately 135,600 bytes of disk storage space from the two mini-disk systems. Tractor feed line printer uses fanfold paper with feed holes in the margins and will produce up to 5 carbon copies. The System Desk has recessed spaces for the Expansion Interface and keybaord with interconnecting wiring concealed. Line printer stand leaves more desk space.

Increases TRS-80’s Internal Memory. The TRS-80 is designed for easy upgrading to a full 16K of RAM memory inside the keyboard unit. Your nearest Radio Shack store can arrange for the exchange of your 4K for 16K chips and add the keypad.

Quality lower case for your Model I display and compatible printer. “Driver” tape included. NOTE: Some non-Radio Shack software will not work with this kit installed. Not intended for use with programs written in upper case format.

When you’ve mastered the Level I programming language, you can move up to higher computing power with Level II. Conversion is easy – we simply exchange the ROM chips in your TRS-80 for chips containing Level II. Your local Radio Shack store can arrange for the exchange. Incorporate Level II into your 4K or 16K RAM Level I TRS-80.

Expansion is a key word in the TRS-80 philosophy. The TRS-80’s modular design lets you expand to just the system you want. Of course, you can add 16K RAM and Level II BASIC to the keyboard unit. Beyond that point, the Expansion Interface becomes the hub of expanded TRS-80 computer systems.

The Expansion Interface measures 4 1/2 x 16 1/2 x 8″ and is designed to sit directly under the video monitor acting as a base for it. The TRS-80’s power supply module, and an identical one for the interface, are housed inside the interface enclosure. Space is also provided for our optional RS-232-C Serial Interface Board.

A cable approximately 6″ long connects the interface to the TRS-80 bus connector. The interface provides output connectors for our TRS-80 printers, disk drives, dual cassette recorders, and an RS-232-C serial port, as well as an extension of the TRS-80 bus, the controller for the electronic circuit needed to install up to four TRS-80 Mini Disk drives, a printer and dual cassette recorders are an integral part of the Expansion Interface, as are the provisions for an extra 16K or 32K of optional RAM. The printer output port is a standard Centronics parallel circuit. This parallel port and our RS-232-C serial port allow connection of a variety of peripheral devices. Pin-out information is provided in the owner’s manual. Each requires 120VAC, 60Hz, 50 watts. U.L. listed.

Expand the disk capacity of your Model I and add the advanced features of Model III’s TRSDOS operating System. After Radio Shack has installed the kit in your Expansion Interface, your existing Model I software may still be used “as is” in single density mode. With the all new Double-Density Disk Operating System, use advanced features and gain increased disk capacity with your current disk drives. With 35-track drives, disk capacity per diskette is increased from 84,000 to 152,000 characters after noemal normal system information. With a 40-track drive, formatted disk capacity is a full 184.000 characters, 737,000 characters with four 40-track drives. COPY moves flles from single-density to double-density format or from double-denslty to single-density. In addition to expanding TRSDOS to include new features, we have added most of Model III’s Disk BASIC enhancements as well. This includes full suppord for variable logical record lengths, and a series of CMD functions that sort strings, cross-reference string variables, delete spaces, and much more. Since our Double-Density TRSDOS contains manu new features, modification of some existing software may be required for use with double density. Even though most BASIC programs and many machine-language programs will run “as is” in Double-Density TRSDOS, Radio Shack applications software is not available or supported for double density operation. Kit includes operating system manual, adapter, and Double-Density TRSDOS operating system diskette. Price does not include required installation.

The TRS-80 Mini-Disk system is a storage medium allowing immediate access to large amounts of data and programs you will need for accounting, inventory control, mailing lists and other jobs. Up to 4 drives can be attached through the expansion interface, furnishing 49,900 to about 307,000 bytes of on-line storage. The first Mini-Disk drive you purchase includes our powerful TRSDOS (Disk Operating System software) and Disk BASIC on diskette. This diskette allows about 50K of user storage space. TRSDOS and Disk BASIC use about 10K of the TRS-80’s RAM, so a minimum of 16K is required, along with Level II and an Expansion Interface.

Each of the diskette’s 35 tracks consists of ten 256-byte sectors. Certain system information and a directory are required on each diskette, leaving 85,760 bytes of space available (each) on the second, third, and fourth drive.

A 13,000-byte program which takes 3 1/2 minutes to load from cassette tape (Level II) will load in less than 20 seconds from disk. And you may read information one file after the other (sequential), or go directly to any sector without reading the preceding files (random).

The system diskette containing TRSDOS and DISK BASIC must always be in your first drive unit. TRSDOS allows you to copy a diskette (BACKUP), even in a one drive system.

Our 5 megabyte Hard Disk System gives you vastly increased data storage with exceptionally fast access and ease of use. Winchester technology can provide dramatic improvements in speed. The advanced operating system’s many superior, user-friendly features make file handling a breeze. Store over 1000 different files per disk system or create files as large as the available space. The directory is alphabetized to make locating and accessing files quick. High-level communication is available through an advanced communication package that allows direct downloading to disk. A print spooler is included, too. The Job Control Language allows you to compile and later execute a predefined series of commands, including screen and audio alerts, conditionals, and user interaction to make many large scale operations virtually automatic. BACKUP, in addition to ordinary backup functions, permits backing up only those files that have been modified, or modified in certain date ranges, or even those that do or do not already exist on the destination disk. When backing up from hard disk to diskettes, the system will span a large file across multiple diskettes and allow easy identification of diskettes when recreating a file on the hard disk. Other features include keyboard typeahead for fast data entry, a versatile printer output formatting program, key redefinition, and more. Extensive user’s manual included. U.L. listed.

Take your TRS-80 system with you wherever you go! One case holds the video monitor, the other holds the keyboard unit, power supply. cassette recorder, cables and cassettes. Black molded vinyl. Hand carry only-not designed for shipping purposes.

Now you can program your TRS-80 to speak. It’s not a pre-recorded human voice, but electronically ‘synthesized” speech projected through a built-in speaker. It plugs into your TRS-80’s bus connector on keyboard or Expansion Interface. Programming spoken words is done by typing combinations of some 60 “phonemes” representing spoken sounds. Requires Level I or II-16K RAM preferred.

Ideal for Engineering, Architectural Work, Drafting, Medical or other Chart Analyses, and much More

Place this unique instrument on a map, chart, or plan of any size. Works with an 11×17″ area. Swivel head allows operation in vertical plane. Input coordinates quickly, easily to your computer. Measure areas, lengths, distances and more. Point and continuous modes. Includes software for basic applications. U.L. Listed.

A breakthrough in computerized classroom instruction! Network I allows teachers to upload and download programs to as many as 16 TRS-80 student stations. LED lamps indicate when a program transfer to or from a station is in progress. The system requires a Model I “host” computer equipped with at least one Mini-Disk drive. Student stations should have Level II BASIC. Network I Controllers can be cascaded to connect more stations. Includes cables. Maximum distance to student station is 30 feet. For Model I and Model III TRS-80’s at 500 baud. U.L. Listed.

Network II allows teachers to upload and download programs to as many as 16 TRS-80 student stations. Requires a Model I or III “Host” computer with at lease one Mini Disk drive and up to 16 Model I or Model III student stations, or a Color Computer with disk for “host” and up to 16 Color Computers for student stations. Controllers can be cascaded to connect more stations. Includes cables.

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Allows easy management of student programs. You can simultaneously load a program into all 16 student systems at either 500 or 1500 baud, depending on the TRS-80 computersused. With optional printer connected to host computer, student programs can be loaded into the host and printed out. Use with Model I/III/4 as host and student stations, or with Color Computers as host and student stations. The Network 2 can be used to transfer ASCII files with Model 100 student stations and either a Model 100 or a Model 4 host. Controllers can be cascaded to connect more stations.

Ideal for anyone who regularly has big transmissions to handle. By quadrupling the baud rate, the DC-1200 will reduce each phone bill to a fourth of what it otherwise would have been. It’s ideal for people who use electronic information services during business hours when long distance rates are at their highest. All you do is plug the power cord into a wall socket, the line cord into the phone jack and the connecting cable to our RS232C-equipped computer. It’s always in “Auto Answer,” so that if a host computer calls you (and your computer is properly configured), you can begin receiving information automatically. The modem automatically adjusts to the incoming baud rate. To originate, you just set the baud rate to match the host or service, run your communication software package, and place the call. And you can upgrade your DC-1200 for automatic origination.

To make your DC-1200 high-speed modem even more useful and versatile, add this handy accessory module. It allows the DC-1200 to automatically dial, as well as answer the phone (with proper computer configuration). This means your computer can operate unattended during low-rate night hours. Plug-in module is a printed circuit board. Installation required (not included).

You can let your TRS-80 communicate with the “outside world” by using our TRS-80 RS-232C Serial Interface Board. It lets you connect the TRS-80 to a variety of accessories such as modems, card reader, line printers and acoustic couplers.

The RS-232-C board mounts inside our Expanasion Interface. A cable is provided for connection to external equipment such as Radio Shack’s Telephone Interface or perhaps your own serial line printer. Included is a comprehensive user’s manual and a cassette tape program which allows the TRS-80 to act as an interactive terminal for communication with a remote timesharing computer.

Radio Shack’s Telephone Interface I lets the TRS-80 “talk” with other computer equipment over the phone! After the proper number has been reached. you simply place your telephone handset in the Interface’s cradle – without a single electrical connection to your telephone lines.

This Radio Shack coupler converts a serial stream of data from the TRS-80 RS-232-C interface into selective audio tones which are then transmitted over standard telephone lines. It can also reverse the process, decoding selective audio tones and feeding them into the TRS-80 throughthe RS-232-C interface. (The RS-232-C allows the TRS-80 to communicate with the outside world via a 2-wire connection, but with electrical signals. Since electrical signals cannot be sent over a voice telephone line, the Telephone Interface converts those signals to audio tones so that the connection can be made over long distances via telephone.) The TRS-80 Telephone Interface I operates in the “originate only” mode, meaning that it can send information to other hardware. It is capable of “two-way communication” only with another computer system having ‘originate and answer” capabilities.

This is the fast way to transfer data from one location to another – by telephone with the Telephone Interface II. It’s a full “originate/answer” acoustic coupler which allows two TRS-80’s to talk to each other. You can also communicate with another computer which has “originate only” capability (like our Telephone Interface I). You can pass all types of data or prograas between computers, or one of you can operate the other’s computer via the telephone lines. No direct connection to the telephone line is required.

It’s very simple to operate. Just dial the phone number at the location of the TRS-80 you desire to communicate with; after the connection is made, each telephone handset is placed on its interface. Now you’re ready to receive and transmit data. Requires RS-232 Serial Interface Card, Expansion Interface, RS-232 Conununications Package and Level II. Adds versatility to your TRS-80.

Connects directly to the telephone line and your computer, eliminating data loss due to microphonic interference. Provides full-duplex operation for TRS-80 Model II, Color Computer, as well as Model I and Model III systems equipped with RS-232 interface. Also provides half-duplex operation for Mode1 I systems without Expansion Interface or RS-232. Features selecable 300/600-baud operation, LED indicators, U.L. listed AC power module. FCC approved.

A fully-programmable direct-connect modem with Auto-Dial and Auto-Answer capability. Automatically dials or answers the phone, receives and transmits data, and even hangs up the phone. Remote and local test modes. LED indicators for On, Off-Hook, Terminal Ready, Carrier Detect, Transmit Data, and Receive Data. FCC Approved.

Attractive and functional. Keyboard and Expansion Interface fit into desktop, with interconnecting wiring concealed. A bay under the desk can house from one to four Mini Disk Drive units. Add a Quick Printer and here’s plenty of workspace left. 27 x 48 x 27″

It’s only 37 3/4 x 23 3/4″ but it holds a TRS-80, cassette recorder, CRT, Expansion Interface, Quick Printer and single or dual disk drives. Space saver was designed to hold your TRS-80 system and still leave ample room for work. The low-cost answer for home or educational users.

The finishing touch – puts it all together! Connects system desk and printer stand for a convenient “work corner.” Mounts on right or left side of desk. Adds approximately 4 square feet of working surface.

Introduces the basics of computer literacy to junior and senior high school students using easy-to-understand approach. Includes teacher’s guide with lesson plans, student activity spirit masters, four wall charts and 80-frame filmstrip with audio cassette. Computer not required.

Illustrates the history of computers for students in grades 4 through 8. Explains what a computer is, what it can do, and how it works. Includes teacher’s guide, six spirit masters and a colorful 22″ x 34″ wall chart.

This informative booklet describes what microcomputers are and how they can be used in classrooms and for administrative purposes. Discusses costs, courseware and other related subjects that are of special concern to the educator.

Ideal for the doctor’s office or small clinic. Prints monthly statements, insurance forms, daily recap, transaction review, aged accounts receivable, and more. Up to 3960 patient accounts with a Model I system or 4200 with a Model III. Up to 200 different procedures and diagnoses. (48K 4-Disk).

Radio Shack’s COBOL (Common Business Oriented Language) is based on the ANSI ’74 COBOL standard, and provides a single-step compiler for fast execution, multikey ISAM for quick data access, COBOL editor for creating and changing source programs, and a DEBUG for program development and testing. lncludes System User’s Guide, COBOL Editor Guide, and an extensive COBOL Reference Manual. (48K 2-Disk)

Lets you program in familiar BASIC, and gain powerful business extensions. Advanced features include single-key ISAM to help organize and retrieve data, cross-reference and interactive DEBUG to speed program development, easy calls to assembly language or other object programs, and 14-digit floatin point decimal formats. (NOTE: Compiler BASIC is intended for program development and not for conversion of existing software. It’s not compatible with Level II or Model III BASIC programs.) Includes Compiler and Run-Time Diskettes, plus detailed 420-page reference manual. (48K 2-Disk).

This program alone will justify your owning a TRS-80! It’s a versatie management and engineering planning and forecasting tool that replaces pencil, calculator, and columnar pad. It lets you create an “electronic worksheet.” Each time you change a variable, VisiCalc updates every related number in seconds! For example, suppose you’re considering leasing or purchasing new equipment. Simply enter the new costs and savings into a VisiCalc spread sheet containing current and projected profit and loss figures. VisiCalc will instantly recalculate every related figure to show the possible effects, and help you decide whether to lease or buy. Instant “what if … ” projections are a real aid for the decision maker. VisiCalc provides numeric accuracy of up to 11 digits, scientific notation, and functions like SIN, COS, TAN, LOG and more-so it’s ideal for solving complex en ineering problems. Produce bar graphs, access Visi 8 alc data files from BASIC, and print any portion of your worksheet with an optional extra printer. (32K l-Disk- Model I only).

A new and expanded version of SCRIPSIT! Features true proportional-spaced printing, multiple line spacing within a document, underlining, double underline, boldface, super and subscript, pause during printing to permit additions from keyboard, and more. User-defined keys can recall up to 127 predefined keystrokes. Comes with training manual, audio cassette course, and reference card. Use with our Profile III Plus program to S enerate form-type letters. (48K, l-Disk).

Provides trend change indications for shot, medium and long term periods based on formulas used by professionals. Maintains portfolio for stocks of your choice. Provides trend recognition aid, not investment counsel.

Compose and edit text on the video display, then use an optional printer to produce correction-free letters and reports. Features centering. headers, footers, global search and more. Save text on cassenbs tor later revision.

Covers addition, subtraction, multiplication, division and number concepts.Skill-building drills for grades 7-12. Reinforces math-concepts introduced by the teacher. Gives immediate feedback for correct and incorrect answers. Includes placement mode as well as promotion and demotion.

Allows students to practice constructing proofs using nine basic posulates of Euclidean geometry. Developed by a high school geometry tracher and tested extensively in the calssroom. Program works out a proof automatically, and guides and tests construction of student’s proofs. Teacher’s manual includes numerous exercises in Euclidean geometry.

The original K-8 Math Program with added student management features. Monitors promotions and demotions, and allows for teacher review of scores. Starts each student in the appropriate lesson each session. Printer optional.

A screen-oriented authoring system that allows teachers to create computer-based lessons. Features full-screen editing, graphics, branching and automatic score-keeping option. Teacher can include a glossary, hints, feedback messages. Printed report includes scores and timings.

A game of elementary deduction which allows you the opportunity to match specific criminals to specific crimes. All of the crimes were committed during the Great Train Robbery in England. After more than a year of searching, Scotland Yard has rounded up seven suspects for the vfour crimes committed – assault, felony theft, arson, and illegal parking. You have up to eight trial (after which the statute of limitations runs out) to match the right criminal to the right crime.

A licensed version of the original arcade game. Get your frogs safely across the road, then guide them to their lily pads on the other side of the river. Optional computer-generated music requires mini-amplifier.

Bring the popular arcade challenge home to your TRS-80. Advance from “Rookie Pilot” to “Combat Ace Pilot” as you enter the floating fortress, destroy enemy defenses, and finally defeat the mighty robot, Zaxxon. Add an optional amplifier for great sound effects.

Generates worksheets and answer sheets from K-8 Math lessons. Teacher can print multiple copies of identical worksheek or worksheets with different problems at the same difficulty level. Worksheets can be saved on disk for later use or editing. Line printer required.

Six laboratory experiment simulations on Kinetic Theory, Charles’ Law, Boyle’s Law, Titration, Conductivity and Solubility. Students control variables in experiments in order to see changing results. Each package includes an instructor’s manual and 25 student experiment books.

Training course designed to help educators create their own lessons using TRS-80 AUTHOR I. Introduces AUTHOR I concepts. Educators are guided through actual lesson creation using text, graphics and special characters.

Store and analyze scouting information on our opponent’s offense. Designed for high school and college levels, CHAMPS prints a variety of listings, charts and statistical reports. Get answers to specific tendency questions in seconds. Includes ten CHAMPS Scouting Manuals which allow even inexperienced scouts to collecl data. Requires 132-column printer.